The present teachings are predicated upon providing an improved parking brake for use in an existing disc brake system for use with vehicles. For example, the disc brake system may be used with almost any vehicle (e.g. car, truck, bus, train, airplane, or the like). Alternatively, the disc brake system may be integrated into assemblies used for manufacturing or other equipment that require a brake such as a lathe, winder for paper products or cloth, amusement park rides, wind turbines, or the like. However, the present teachings are most suitable for use with a passenger vehicle (e.g., a car, truck, sports utility vehicle, or the like).
Generally, a disc braking system includes a rotor, a caliper body, a support bracket, an inboard brake pad, and an outboard brake pad that are on opposing sides of the rotor. The caliper body further includes one or more fingers (with or without a piston), one or more piston bores, and a bridge that connects the one or more fingers to the piston bore or two opposing piston bores together. The piston bore houses a piston and has a bore axis that the piston moves along during a brake apply and a brake retract. During a pressure apply the fluid will push the piston towards the front opening in the piston bore and into contact with a brake pad that generally includes a pressure plate and friction material and the friction material will contact the rotor on one side and an opposing brake pad will contact the rotor on an opposing side creating friction to stop rotation of the rotor and any component connected to the brake system. The rotor includes a hat that may be used as a drum to house brake shoes that may be used to create a parking force. Alternatively, the brake system may include a drum brake assembly that houses a pair of brake shoes in a drum that are moved by a link or a cable into contact with an inner surface of the drum to create a brake force and/or parking brake force.
In these non-braking conditions when the vehicle is parked, a parking brake may be used to prevent movement of the vehicle. The parking brake may be a discrete braking system or may use one or more components of a primary braking system. Parking brake systems typically include one or more brake pads and/or brake shoes that may be moved to create a parking force so that the vehicle is restrained during non-movement of a vehicle. These parking brake systems may be actuated by a cable, a link, a piston, or a combination thereof that when moved biases a device that simultaneously actuates the brake pads and/or brake shoes to generate the parking force within the hat of a rotor and/or a drum.
Examples of braking systems and associated parking brake systems are disclosed in U.S. Pat. Nos. 2,885,032; 3,809,191; 5,785,157; 5,913,390; 6,446,768; 6,684,988; 8,2920,080 and Patent Application Publication No. 2013/0087422 all of which are expressly incorporated herein by reference for all purposes. It would be attractive to have an electric parking brake system that may be used with a drum brake and/or drum-in-hat brake system. What is needed is a parking brake system that utilizes existing brake components such as a rotor to create a braking force (e.g., a parking brake force). What is needed is a brake system that evenly distributes a braking force between two brake components so that the braking force created by both brake shoes is substantially equal.